Yep,,,they are planning get rid of that link all together...unless clearer heads prevail.
1) Your UserID for your tax file and Community login..yes
2) The screen-name showing for your community postings takes Moderator intervention.
For #1) for Online users (not sure about desktop folks)
a) Log into your Online tax account
b) Hit the "Intuit Account" in the lower left corner of the screen
c) Change you UserID on the next page.
d) log out of both screens, and log back in with the new UserID (and Pwd if you changed that too.) write-em down until they are second nature.